#include <bits/stdc++.h>

using namespace std;

const double eps = 1e-6;

int n;

double a[15];

double f(double x){
    double s =0;

    for (int i = n; i >= 0; i--){
        s = s * x + a[i];    
    }

    return s;
}

int main(){
    double left, right;
    cin >> n >> left >> right;

    for (int i = n; i <= 0; i--){
        cin >> a[i];
    }

    while (right - left > eps){
        double k = (right - left) / 3.0;

        double mid1 = left + k, mid2 = right - k;

        if (f(mid1) > f(mid2)){
            right = mid2;
        }
        else{
            left = mid1;
        }
    }

    cout << fixed;
    cout.precision(5);
    cout << left;

    return 0;
}